Driving requires your full attention, both physically and mentally. Sudden changes in your ability to drive, for any reason, increase your risk of a crash. Knowing when it's time to pull over can save you from filing a crash-related car insurance claim -- and may even save your life.
Here are 10 scenarios when it most likely makes sense to get off the road.
In general, any medical situation that prevents you from driving safely is a good reason to pull over, says Dr. Keith Borg, a pediatric and adult medicine specialist at the Medical University of South Carolina. After you pull over to a safe location, put on your car's flashers and call 911, Borg says.
The following health issues may indicate you're about to lose consciousness or otherwise lose control of your vehicle, says Dr. Jacob Teitelbaum, medical director of the national Fibromyalgia and Fatigue Centers and author of "From Fatigued to Fantastic!"
1. Chest pain or tightness, especially if it's radiating down your left arm or causing a cold sweat. This suggests a possible heart attack, which can be accompanied by loss of consciousness. Chew on an aspirin if you have one available while waiting for emergency personnel, Teitelbaum says.
2. Sudden weakness or loss of function on one side of your body or loss of ability to speak. This may indicate an impending stroke. It's best to stop your car and call 911.
3. Racing heart, dizziness or both. This may stem from abnormal heart rhythm, which also could trigger loss of consciousness. If you're a diabetic, dizziness may suggest low blood sugar. If you can't handle this on your own, you should dial 911.
4. Vertigo. This type of dizziness makes it feel as if you (or the world) are spinning around in a circle. This most often involves an ear problem but can be disorienting enough to cause a crash, so it's best to take a break from driving -- even if the symptoms have passed.
5. Shakiness, sweatiness, light-headedness and nausea may be symptoms of low blood sugar in diabetics, says Dr. Dana Simpler, an internist and primary care practitioner at Mercy Medical Center in Baltimore. Pull over and eat something; if the symptoms continue to persist, call 911.
"Diabetics may want to keep hard candies -- even packets of sugar -- in their glove compartment for such emergencies," Simpler says.
Sudden changes in the mechanics of your car often mean you should stop your car and check out the problem.
6. Sudden loss of power steering accompanied by the appearance of the "check engine" light. Greg Burchette, owner of Bridgewater Motorworks in Bridgewater, N.J., says this may not be signaled by any sound at all. Loss of power steering control could come from a broken belt or a loss of power steering fluid.
7. Flashing red light on your dashboard. Dave Riccio, owner of Tri-City Transmission in Tempe, Ariz., says this frequently is a sign of trouble. Lights that typically turn red are the "engine overheat" light and the battery light, but there may be others, depending on the year, make and model of your car.
8. Bumping and shaking with the check engine light flashing could be from a cylinder misfire. In this case, you should pull over immediately, says Tim Nelson, service manager at Virginia Auto Service in Phoenix.
9. Burning smell. This could be caused by burning fluids from damaged or missing hoses or by an engine malfunction. Although it's rare, burning fluids can cause engine fires, Nelson says. Another potential culprit: antifreeze burning from a radiator leak. If you continue driving under these circumstances, you could damage your car and put you and other motorists in harm's way.
10. Sudden change in visibility. A massive downpour, thick fog, snow, ice or any other massive weather-related headache indicates it's time to pull over. Wait until the weather clears or you can fix the problem, such as removing ice from the windshield, before getting back on the road.